Graphene first appeared in laboratory in the year of 2004, at that time the two scientists in the University of Manchester, i.e., Andre Jim and Kostya Novoselov, found that they could obtain a graphite flake that became thinner and thinner by a very simple method. That is, they peeled the graphite flake from the graphite, adhered the two sides of the flake onto a special tape, and after tearing the tape, the graphite flake was divided into two flakes. By continuing the above operation, the flake became thinner and thinner. Finally, they obtained a flake only consisted of one layer of carbon atom, that is, graphene. From then on, the method for preparing graphene was emerged abundantly, and currently there are mainly two preparation methods as follows:
1. Chemical vapor deposition method provides an controllable and effective method for preparing graphene, which comprises placing a planar substrate, such as metal film, metal single crystal etc. into a precursor that can decompose at high temperature, such as the atmosphere of methane, ethylene etc., the carbon atom is deposited on the surface of the substrate by high temperature annealing so as to form graphene, and finally the separate graphene flake can be obtained after removing the metal substrate by chemical etching. The growth of the graphene such as the growth rate, the thickness, the area etc. can be adjusted by selecting parameters such as the type of the substrate, the growing temperature, the flow rate of the precursor etc. However, the biggest disadvantage of this method consists in that because of the strong interaction of the obtained graphene flake with the substrate, many properties of the single layer of graphene are lost and the continuity of the graphene is not good.
2. SiC thermal decomposing method. In this method, the single crystal SiC is heated so as to remove Si by decomposing the SiC on the surface, and the remaining carbon forms graphene. However, the single crystal SiC used in the SiC thermal decomposition is very expensive and the grown graphene is distributed in a shape of island, the layer is not uniform and the size is small. Thus, it is difficult to prepare graphene with a large area by this method.